BME688 Upper limit of gas resistance value and step in graph

[yos]

Hello,

I'm trying BME688 and I have 2 questions about gas resistance value.

1. The resistance value at the low heating temperature in the steps of the heater profile seems to saturate frequently at 102400000. Does this mean that it reach the upper limit of the measurable resistance value?
Also, even if resistance reach the upper limit frequently like this, can it be used for training etc. as normal data?

2. When acquiring room air data, I often see a stepped gap in my graph. What could be the possible cause?

For reference, I attach a graph when measuring air.
I am using HP354/RDC1-0 with BME688 Development kit.
The red arrow points to the first question, and the blue arrows point to the second question.

[BSTRobin]

Hi yos,

For first question, in what air environment did you test?

[BSTRobin]

Hi yos,

For question1, low temperature and unsensitive gas may cause saturation value, so it's necessary to make clear what gas you tested. And it's better not to use such the data, or you can change another sensor to have a try;
For question 2, I think it may be caused by some external gas, because the room is not a closed environment.

[yos]

Hi BSTRobin, thank you for the reply.

The graph I attached the other day is from when I measured the indoor air in the office to check the operation.
I have confirmed that such saturation does not occur as the resistance value decreases while being exposed to something with an easily identifiable odor, such as coffee.
I asked this question because I was wondering if it is okay to handle such saturated data as normal air data when learning with AI-Studio.

[BSTRobin · Accepted solution]

Hi yos,

We think the such saturated data shouldn't be regarded as normal data. Because they are all in step 1, usually which was caused by low temperature, firstly you should check which heater profile the you used, and we suggested using HP-354, because the low temperature which you used will cause the saturated data.
And then if you changes the HP, there is still saturation value, trying another BME sensor if possible.